Foreigners seeking to adjust their immigration status in the United States to secure green cards will have to do so from outside the country via the state department, the US Citizenship and Immigration Services (USCIS) said on Friday, in a move criticized by aid groups, policy analysts and immigration attorneys.

USCIS announced the move in a policy memo, which directed officers to consider relevant factors and information on a case-by-case basis when determining whether extraordinary relief is warranted.

The green card process had been unchanged for more than 60 years, marking the latest significant move by the Trump administration on immigration policy.

“An alien who is in the US temporarily and wants a Green Card must return to their home country to apply,” said the US Department of Homeland Security (DHS), which has oversight of USCIS.

“This policy allows our immigration system to function as the law intended instead of incentivizing loopholes.”

According to an analyst with the Cato institute, more than 1 million legal immigrants in the US are waiting on their green cards.

People apply for green cards in two separate ways: by applying at a US consulate abroad, or by applying for a green card while already in the US, which is called an “adjustment of status”.

With the new USCIS policy, many green card applicants in the US will probably be required to leave while their cases are processed – particularly affecting mixed-status families nationwide by forcing green card applicants to leave jobs, homes and relationships for an unknown amount of time. The agency is already struggling with a backlog of visa and green card cases.

It is unclear how currently pending green card cases will be affected.

HIAS, an aid group that provides services to refugees, among other groups of immigrants, said USCIS was forcing survivors of trafficking and abused and neglected children to return to the dangerous countries they fled in order to process their applications for green cards granting them permanent residency in the US.

Friday’s policy change is the latest in a series of steps taken by Donald Trump over the last year to tighten immigration to the United States. Last year, the Trump administration moved to shorten the duration of visas for students, cultural exchange visitors and members of the media.

In January, the state department announced that it had revoked more than 100,000 visas in the second Trump administration. The administration has also attacked other immigrants with legal status in the US, like refugees and other protected immigrants.

Reuters contributed reporting